JP2010060002A - Spline shaft and method of manufacturing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a durable spline shaft structuring a shaft to be extended/shrunken through a spline in a steering device and enable to remarkably strongly install a resin cover, which improves extending/shrinking performance by the spline, to the spline, and to provide a method of manufacturing the same. <P>SOLUTION: This spline shaft is structured of: a spline part 2 formed of a plurality of tooth profile parts 21 in the circumferential direction in an axial end side of a shaft part 1; a transmission shaft A formed of a main recessed part 3 crossing the axial direction of the spline part 2 and formed along the circumferential direction and having a bottom surface 31 deeper than bottom parts 22 of the spline part 2 and auxiliary recessed parts 4 formed on both sides of the main recessed part 3 in the axial direction and formed shallower than the main recessed part 3 and deeper than the bottom parts 22 of the spline part 2; and a resin cover part 5. The resin cover part covers each tooth profile part 21 and each bottom part 22 of the spline part 2, and fitted in the circumferential direction of the main recessed part 3 and the auxiliary recessed parts 4. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention constitutes a shaft that expands and contracts via a spline in a steering device, and a resin coating for improving the stretchability by the spline can be attached to the spline very firmly and has a durability. The present invention relates to a spline shaft that can be provided and a manufacturing method thereof.

In general, a steering shaft in a steering apparatus for an automobile has a configuration that can be expanded and contracted via a spline. It is widely known that a part of the spline is covered with a resin material layer in order to reduce friction during sliding between the splines. As a conventional technique of this type, for example, in Patent Document 1, at least one annular groove having a diameter smaller than the diameter of the root circle of the spline is provided on the conduction shaft. Then, the conductive shaft is accommodated in the mold cavity of the injection mold, and the molten resin is poured into the position of the annular groove to cover the outer peripheral portion where the spline of the conductive shaft is formed. In this patent document 1, it becomes possible to supply resin regularly and uniformly to the outer peripheral part in which the spline was formed by flowing resin from the location of the annular groove.
Japanese Patent Publication No.2-19325

  However, in Patent Document 1, the resin part covering the spline may be peeled off when the conductive shaft is taken out from the mold. Accordingly, an object (technical problem) of the present invention is that a shaft that expands and contracts via a spline in a steering device can be attached to a spline with a resin coating for improving the axial stretchability and is durable. The present invention relates to a spline shaft that can be made and a manufacturing method thereof.

  Therefore, as a result of earnestly researching the inventor in order to solve the above-mentioned problems, the invention of claim 1 is a spline part comprising a plurality of tooth profile parts on the axial end side of the shaft part and in the circumferential direction, A main recess formed perpendicularly to the axial direction of the spline portion and along the circumferential direction and having a bottom surface deeper than the tooth bottom portion of the spline portion; and both sides of the main recess in the axial direction and shallower than the main recess The spline portion includes a transmission shaft including a sub-recess portion formed deeper than the tooth bottom portion, and a resin coating portion. The spline portion covers each tooth profile portion and the tooth bottom portion, and the main recess portion and the sub-recess portion. The above problem is solved by using a spline shaft filled in the circumferential direction.

  According to a second aspect of the present invention, the above problem is solved by using a spline shaft in which the diameter of the root circle of the spline portion is larger than the diameter of the shaft portion. According to a third aspect of the present invention, the above-described problem is solved by using a spline shaft in which the cross-sectional shape orthogonal to the circumferential direction of the main recess is a substantially rectangular shape in the above-described configuration. According to a fourth aspect of the present invention, the above-mentioned problem is solved by using a spline shaft in which the cross-sectional shape perpendicular to the circumferential direction of the sub-recess is a substantially rectangular shape in the above-described configuration.

  The invention according to claim 5 is a spline portion comprising a plurality of tooth profile portions in the axial direction end side of the shaft portion and in the circumferential direction, and the spline portion formed perpendicularly to the axial direction of the spline portion and along the circumferential direction. A transmission shaft comprising a main concave portion having a bottom surface deeper than the tooth bottom portion and a sub-recess portion formed on both sides in the axial direction of the main concave portion and shallower than the main concave portion and deeper than the tooth bottom portion of the spline portion. Is inserted and arranged in a mold having a tooth forming shape part slightly larger than the spline part, and the position of the main recess is aligned with the pouring path provided in the mold, and the main recess is extended from the pouring path. The above problem was solved by using a method for manufacturing a spline shaft in which molten resin is poured into the spline portion and the sub-recessed portion and a resin coating portion is formed with molten resin.

  In the invention of claim 1, the main recess is formed along the circumferential direction perpendicular to the axial direction of the spline portion and has a bottom surface deeper than the tooth bottom of the spline portion, The spline part is formed deeper than the tooth bottom part, and is formed shallower than the main concave part. Therefore, in the structure in which the resin covering portion is formed on the spline portion, the main locking portion made of the strongest and strong annular resin is formed in the main recess portion. Further, the sub-recess portion is also made of an annular resin deeper than the tooth bottom portion of the spline portion, and a sub-engagement portion having a smaller volume than the resin coating at the main recess portion is formed.

  The main locking portion is formed at a substantially central position in the axial direction of the resin coating portion, and can firmly fix the resin coating portion to the spline portion. Located on both sides of the main locking portion in the axial direction, it serves to reinforce the portions on both sides in the axial direction of the resin coating portion. With such a configuration, it is possible to make the resin coating portion stronger than the spline portion, and to further strengthen the strength of the entire coating of the resin coating portion.

  In particular, when the resin coating portion is injection molded by a mold on the spline portion, when the molding of the resin coating portion is completed and the conductive shaft is extracted from the mold, the sub locking portion made of resin formed in the sub recess portion It can be made difficult to peel off from the spline part, and the finish of the resin coating part can be made extremely good. Further, since the sub-recess is formed shallower than the main recess, the spline can be sufficiently maintained in rigidity and strength despite the formation of the sub-recess. Can be excellent.

  According to a second aspect of the present invention, the diameter of the root circle of the spline portion is larger than the diameter of the shaft portion. In addition, the diameter of the shaft portion can be equal to or larger than that, and the rigidity and strength of the transmission shaft can be maintained well.

  In the invention of claim 3, since the cross-sectional shape perpendicular to the circumferential direction of the main recess is substantially rectangular, the volume of the main recess can be increased efficiently, and the main recess is rectangular. In addition, the biting structure with respect to the spline portion is further strengthened, and the resin coating portion can be fixed extremely firmly to the spline portion. In the invention of claim 4, the cross-sectional shape orthogonal to the circumferential direction of the sub-recess portion is substantially rectangular, so that when the resin coating portion is formed on the spline portion with a mold, the molten resin is In particular, even at a position away from the main recess, the molten resin entering from the main recess can be efficiently filled into the sub-recess.

  According to a fifth aspect of the present invention, the molten metal is inserted and arranged in a mold having a tooth forming shape part slightly larger than the spline part, and the position of the main concave part is aligned with a pouring path provided in the mold, While the molten resin is poured from the path into the main recess, a resin coating portion is formed of the molten resin in the spline portion and the sub-recess, so that the main recess of the conduction shaft is the mold pouring path of the mold. Since the bottom surface of the main concave portion is deeper than the spline portion bottom, the molten resin continuously spreads from the pouring channel in the circumferential direction of the spline portion. Further, since the sub-recess is also formed deeper than the tooth bottom of the spline portion, the molten resin continuously spreads from the main recess along both axial sides of the spline portion, and the molten resin is spread in the circumferential direction of the spline portion and It is possible to supply the resin-coated portion in an excellent manner by regularly and uniformly supplying the tooth profile portion and the tooth bottom portion in the axial direction.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. First, in the present invention, the spline shaft is a shaft member that constitutes a steering shaft, in particular, an outer spline is formed, is used together with the shaft on which the inner spline is formed, and expands and contracts in the axial direction. is there. As shown in FIGS. 1A, 1 </ b> B, and 3 </ b> B, the spline shaft includes a transmission shaft A and a resin coating portion 5. The transmission shaft A is mainly composed of a shaft portion 1 and a spline portion 2 as shown in FIGS. The shaft portion 1 is a hollow metal tube material, and a spline portion 2 is formed at a position from the axial end portion of the shaft portion 1.

  The spline portion 2 is formed with a plurality of tooth profile portions 21, 21,... (See FIGS. 2C, 2D, and 3A). Each tooth profile portion 21 is formed in a linear shape along the axial direction of the shaft portion 1. Between the tooth profile portions 21 and 21 adjacent to each other in the circumferential direction is a tooth bottom portion 22, and a virtual circle passing through the tooth bottom portions 22, 22,... Is referred to as a tooth root circle Qa [FIGS. ), See (D)]. The diameter Da of the root circle Qa is slightly larger than the diameter Do of the outer periphery of the shaft portion 1 (see FIGS. 2A and 2B). That is, the spline portion 2 is formed such that the tooth bottom portion 22 is positioned further outward in the diameter direction than the outer peripheral side surface of the shaft portion 1. Specifically, a thick shaft region is formed on the outer periphery of the shaft portion 1, and the spline portion 2 is formed in the thick shaft region (see FIGS. 2A and 2B).

  As shown in FIGS. 1 (A), 2 (C), (D), and FIG. 3 (A), the spline portion 2 is formed with a main recess 3 and a sub-recess 4 along the circumferential direction. ing. The main concave portion 3 is formed as an annular groove shape along the circumferential direction of the shaft portion 1, and is located at a substantially central position in the axial direction of the spline portion 2 [FIGS. 2 (A) and (B). And FIG. 3 (A)]. The main recess 3 has a substantially square cross-sectional shape perpendicular to the circumferential direction (see FIGS. 2A and 2B). Specifically, the main recess 3 includes a bottom surface 31 and side surface portions 32 and 32 formed on both sides of the bottom surface 31 in the width direction.

  Both side surface portions 32, 32 are formed so as to gradually spread outward in the diametrical direction of the spline portion 2, and the cross-sectional shape of the main concave portion 3 is formed to be a substantially inverted trapezoidal shape. It is a thing. The position of the bottom surface 31 of the main recess 3 is formed to be the same surface or deeper than the position of the tooth bottom portion 22 of the spline portion 2. That is, if the diameter of the virtual circle Qb passing through the bottom surface 31 of the main recess 3 is Db, the diameter Db of the virtual circle Qb is smaller than the diameter Da of the root circle Qa, and Db <Da [FIG. 2 (B) and (C)].

  The sub-recess 4 is formed in an annular groove shape along the circumferential direction of the shaft portion 1, similarly to the main recess 3, and the main recess 3 along the axial direction of the spline portion 2. These are formed at appropriate intervals on both sides in the axial direction. The sub-recess 4 has a substantially square cross-sectional shape perpendicular to the circumferential direction (see FIGS. 2A and 2B). Further, the sub-recess 4 may be formed in a semi-elliptical shape (see FIG. 4), a substantially semi-circular shape, a semi-elliptical shape, or a substantially U-shape in a substantially V-shaped cross section.

  The deepest position 41 of the sub-recess 4 is formed so as to be shallower than the bottom surface 31 of the main recess 3 and deeper than the tooth bottom 22 of the spline part 2 as shown in FIG. Has been. That is, if the diameter of the virtual circle Qc passing through the deepest position 41 of the sub-recess 4 is Dc, the diameter Dc of the virtual circle Qc is smaller than the diameter Da of the root circle Qa and the diameter Db of the virtual circle Qb. Bigger than. That is, Db <Dc <Da (see FIGS. 2B, 2C, and 2D).

  As shown in FIGS. 5 (D) and 5 (E), the resin coating portion 5 is formed from a synthetic resin through a mold B described later, and each tooth profile portion 21, 21 of the spline portion 2. ,... And the respective tooth bottom portions 22, 22,... And the tooth bottom portions, and are filled in the circumferential direction of the main recess 3 and the sub-recess 4. As shown in FIGS. 1A, 1 </ b> B, and 1 </ b> C, the resin coating portion 5 is formed as a thin resin coating layer on the tooth profile portion 21 and the tooth bottom portion 22. In the resin coating portion 5, the portion filled in the main recess 3 becomes a main locking portion 51, and the two portions filled in the sub-recess 4 become sub-locking portions 52.

  The main locking portion 51 has the same cross-sectional shape as that of the main recess 3, and the sub-locking portion 52 has the same cross-sectional shape as that of the sub-recess 4. The resin coating portion 5 is firmly fixed to the spline portion 2 by the main locking portion 51, and the two auxiliary locking portions 52, 52 are thin at both axial positions of the spline portion 2. While reinforcing the covering portion, the resin covering portion 5 can be made difficult to come off from the spline portion 2. In addition, since the sub-recess 4 is shallower than the main recess 3, the amount of reduction in the shape of the tooth bottom 22 of the spline 2 can be minimized, and the rigidity of the transmission shaft A can be reduced. The strength can be kept large, and the strength and rigidity of the resin coating portion 5 can be improved.

  As described above, the structure in which the resin coating portion 5 is formed on the spline portion 2 is formed as the main locking portion 51 made of the largest and strong annular resin at the main recess portion. Further, the sub-recess 4 is also formed as a sub-locking portion 52 made of an annular resin deeper than the tooth bottom portion 22 of the spline portion 2 and having a smaller volume than the resin coating of the main recess 3.

  The main locking portion 51 of the resin coating portion 5 is formed at a substantially central position in the axial direction of the resin coating portion 5 and can fix the resin coating portion 5 to the spline portion 2 very firmly. In addition, the sub-recess 4 is formed on both sides of the main locking portion 51 in the axial direction, and particularly serves to reinforce portions on both sides of the resin coating portion 5 in the axial direction. With such a configuration, the resin covering portion 5 can be prevented from coming off from the spline portion 2, and the strength of the entire coating of the resin covering portion 5 can be further strengthened.

  In particular, when the resin coating portion 5 is injection-molded on the spline portion 2 by a mold B which will be described later, when the molding of the resin coating portion 5 is completed and the conductive shaft A is extracted from the mold B, it is formed in the sub-recess 4. The sub-locking portion 52 made of resin can be made difficult to peel off from the spline portion 2, and the finish of the resin coating portion 5 can be made extremely good. Further, since the sub-recess 4 is formed shallower than the main recess 3, the rigidity and strength of the spline portion 2 can be sufficiently maintained despite the formation of the sub-recess 4, and the spline shaft is rigid. And excellent strength.

  Next, the manufacturing method of the spline shaft of this invention is described. As shown in FIGS. 5A and 5B, the mold B includes a resin coating portion molding mold 6 and a presser mold 7. The resin coating portion molding die 6 has a through-hole-shaped resin coating portion molding portion 61 and a pouring passage 62 (see FIGS. 5B and 5C). The resin coating portion molding portion 61 is formed slightly larger than the shape of the spline portion 2, and each tooth profile portion 21 of the spline portion 2 and the spline portion 2 are inserted in the resin coating portion molding portion 61. A slight gap is formed between each tooth bottom portion 22 and the resin coating portion molding portion 61 (see FIG. 5E). The pouring passage 62 communicates with the resin coating portion molding portion 61, and a pouring port 62 a of the pouring passage 62 is formed on the outer side of the resin coating portion molding die 6. An outlet 62b is formed on the molding portion 61 side.

  The presser die 7 includes a presser plate 71 composed of two half plates 71a and 71a. Each half plate 71 a is formed with a semicircular hole portion 72 a, and the two semicircular hole portions 72 a and 72 a are configured as a through hole 72 by combining the two half plates 71 a and 71 a. The through-hole 72 is configured to accommodate the shaft portion 1 of the transmission shaft and close both side openings of the resin coating portion molding portion 61 of the resin coating portion molding die 6 (see FIGS. 6 and 7). ). One of the two half plates 71a, 71a of the presser mold 7 is provided with a pin 73, the other is provided with a connection hole 74 into which the pin 73 is inserted, and the pin 73 of one half plate 71a is connected to the other. The half plates 71a and 71a are connected to each other by being inserted into the connection hole 74 of the half plate 71a.

  First, the spline part 2 of the transmission shaft A is inserted into the resin coating part molding part 61 of the resin coating part molding die 6 (see FIGS. 5D and 5E). At this time, it sets so that the position of the main recessed part 3 of the spline part 2 and the position of the outflow port 62b of the pouring channel 62 may correspond. Moreover, it installs so that the clearance gap between the said resin coating part shaping | molding part 61 and the spline part 2 may become uniform [refer FIG.5 (E), FIG.8 (A)]. In order to allow the spline portion 2 to be accurately installed with respect to the resin coating portion molding portion 61, it is preferable to previously provide a mark that can be aligned between the mold B and the transmission shaft.

  Then, the molten synthetic resin is poured from the pouring port 62a of the resin coating portion molding die 6 of the die B. Then, the molten resin flows into the main concave portion 3 from the outlet 62b of the pouring passage 62, the molten resin passes through the gap between the tooth profile portions 21, and flows into the sub concave portion 4, and the molten resin further flows into the resin coating portion. The resin coating portion 5 is molded by filling the molding portion 61 and curing the molten resin. Next, the respective half plates 71 a and 71 a of the presser mold 7 are separated from the resin coating part molding die 6, whereby the transmission shaft A is drawn out from the resin coating part molding die 6. At this time, the resin coated portion 5 is formed on the spline portion 2 [see FIG. 8C].

  The mold B is provided with an air escape portion 8. The air escape portion 8 is provided in one or both of the resin coating portion molding die 6 and the presser die 7. When the resin coating portion 5 is molded with the die B, It serves to prevent the air from accumulating inside the mold B so that the molten resin can be uniformly fed into every corner of the mold B. As a specific example of the air escape portion 8, when it is first provided in the resin coating portion molding die 6, it is formed as a substantially groove shape at an appropriate position of the opening of the resin coating portion molding portion 61 ( (See FIG. 6). A part of the air escape portion 8 of the resin coating portion molding die 6 is exposed to the outside when the presser die 7 is attached to the resin coating portion molding die 6. As shown in (C), a substantially L-shaped cut portion is formed along the axial direction of the semicircular hole portions 72a, 72a of the half plates 71a, 71a of the presser die 7. Further, as shown in FIGS. 7D and 7E, a substantially L-shaped cut portion is formed on either side of the half plates 71a and 71a of the presser mold 7 and along the width direction. Is.

(A) is a side view showing a partial cross section of the spline shaft in the present invention, (B) is an enlarged view of (A) part of (A), (C) is an end view taken along arrow Xa-Xa of (B), ( (D) is an end view taken along the line Xb-Xb of (B), and (E) is an end view taken along the line Xc-Xc of (B). (A) is an enlarged vertical side view of the main part of the transmission shaft, (B) is a further enlarged vertical side view of the main part of (A), (C) is an end view taken along arrow Xd-Xd of (A), (D). FIG. 6 is an end view taken along the arrow Xe-Xe in FIG. (A) is a side view of a spline part, (B) is a side view in which a resin coating part is provided on the spline part, and (C) is an enlarged vertical side view of a main part of the resin coating part. It is a principal part expanded sectional view of the spline shaft in which the secondary recessed part of another shape in this invention was formed. (A) is a longitudinal side view of the mold, (B) is a cross-sectional view of the mold in a state where the resin-coated portion molding mold and the presser mold are separated, and (C) is an Xf-Xf arrow view of (B). End view, (D) is a longitudinal side view of the spline shaft with the spline portion disposed in the mold, and (E) is an enlarged longitudinal side view of the main part of (D). It is a perspective view of a resin coating part molding die. (A) is a partially cut front view of the presser mold, (B) is a separated front view of the presser mold, (C) is a cross-sectional view taken along the Xg-Xg arrow of (B), and (D) is (B ) Is a separated rear view of the presser die provided with an air escape portion different from FIG. 4, (E) is a cross-sectional view taken along the line Xh-Xh in (D), and (F) is an enlarged view of the portion (B) in (E). is there. (A) is a resin coating part molding process diagram in a state where molten resin is injected from a pouring channel of the mold, (B) is a resin coating part molding process diagram in a state where the resin coating part is molded, and (C) is a transmission. It is an expansion vertical side view of the state figure which extracts a shaft.

Explanation of symbols

A ... Transmission shaft, 1 ... Shaft portion, 2 ... Spline portion, 21 ... Tooth profile portion, 22 ... Tooth bottom portion,
DESCRIPTION OF SYMBOLS 3 ... Main recessed part, 31 ... Bottom, 4 ... Sub recessed part, 5 ... Resin coating | coated part, B ... Mold, 62 ... Pouring channel.

Claims (5)

  A spline portion formed of a plurality of tooth profile portions in the axial direction end side of the shaft portion and in the circumferential direction, and is formed along the circumferential direction perpendicular to the axial direction of the spline portion and deeper than the tooth bottom portion of the spline portion. A power transmission shaft comprising a main concave portion having a bottom surface, a sub concave portion formed on both sides in the axial direction of the main concave portion and shallower than the main concave portion and deeper than the tooth bottom portion of the spline portion, and a resin coating portion The spline shaft is characterized by covering each tooth profile portion and tooth bottom portion of the spline portion and being filled in the circumferential direction of the main concave portion and the sub concave portion.   2. The spline shaft according to claim 1, wherein a diameter of a root circle of the spline portion is larger than a diameter of the shaft portion.   3. The spline shaft according to claim 1, wherein a cross-sectional shape orthogonal to the circumferential direction of the main recess is a substantially rectangular shape.   4. The spline shaft according to claim 1, wherein a cross-sectional shape orthogonal to a circumferential direction of the sub-recess is a substantially rectangular shape. 5.   A spline portion formed of a plurality of tooth profile portions in the axial direction end side of the shaft portion and in the circumferential direction, and is formed along the circumferential direction perpendicular to the axial direction of the spline portion and deeper than the tooth bottom portion of the spline portion. A transmission shaft composed of a main recess having a bottom surface and sub-recesses formed on both sides in the axial direction of the main recess and shallower than the main recess and deeper than the tooth bottom of the spline portion, than the spline portion. Inserted into a mold having a slightly larger tooth forming portion, the position of the main recess is aligned with the pouring channel provided in the mold, and molten resin is poured from the pouring channel into the main recess. On the other hand, a method for manufacturing a spline shaft, wherein a resin coating portion is formed of molten resin in the spline portion and the sub-recess portion.

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